1. Field of the Invention
The invention relates in general to one or more optical networking components and, more particularly, to add/drop nodes.
2. Background of the Invention
Optical networks include one or more optical fibers that each carry several channels of information. Each channel of information is carried in a light signal having a different wavelength. A variety of optical networks also include one or more add/drop nodes where one or more channels of information is added to an optical fiber or dropped from an optical fiber.
Many add/drop nodes allow a first signal of a channel of information to be dropped from an optical fiber and allow another signal of the same channel to be added to the same optical fiber. Different information can be carried within the channel using the different signals. For instance, the first signal of the channel can be destined for a first city and the second signal can originate at the first city and be destined for a second city. When the add drop node is located in the first city, the first signal on the channel can be dropped from the optical fiber for processing in the first city. The second signal on the channel can be added to the fiber optic and directed to the second city by the network.
Add/drop nodes can be tunable. A tunable add/drop node allows the channel of information that is dropped and/or added at a particular add/drop node to be selected. When the add/drop nodes changes the channel that is added and/or dropped from a first channel to a second channel, the add/drop node must scan through each of the channels between the first channel and the second channel. As a result, a fiber optic carrying a channel dropped at the node would temporarily carry each of the channels between the first channel and the second channel. Hence, information carried in the channels between the first channel and the second channel can be lost as the add/drop node is tuned.
There is a need, therefore, for an add/drop node that can be tuned without loss of information.